Twin Falls Idaho (movie, 1999)

Francis and Blake Falls are Siamese twins who live in a neat little room in a rundown hotel. While sharing some organs, Blake is always fit and Francis is very sickly. Into their world comes a young lady, who turns their world upside down. She gets involved with Blake, and convinces the two to attend a Halloween party, where they can pass themselves off as wearing a costume. Eventually Francis becomes really ill, and they have to be separated. They then face the physical and mental strains that come from their proposed separation.